The Effect of Different Levels of Sodium Nitrate on the Physicochemical Parameters and Nutritional Value of Traditionally Produced Fermented Loins

This study evaluated the effect of sodium nitrate reduction on the following parameters: thiobarbituric acid reactive substances, the color parameters (CIE L* a* b*), total heme pigments, heme iron content and nutritional value related to N-nitrosamines content as well as nitrate and nitrite residues of traditionally produced fermented loins. Raw loins (m. longissimus thoracis et lumborum) and fermented products with different levels of nitrate added (0, 50, 100, 150 mg kg−1) were tested during six months of vacuum storage. The reduction of nitrate did not lead to statistically significant changes in total pigment content as well as heme iron content in fermented loins at the end of processing and during storage. Water activity did not differ statistically significantly between the formulations. Fermented loins at the end of processing revealed residual sodium nitrite levels of <10 mg kg−1, while the amount of nitrate residue depended on the level added during production, obtaining the highest value of 19.0 mg kg−1 for the sample with the highest nitrate addition. The level of nitrosamines was <5 µg kg−1 in all samples, which proves their chemical safety. In conclusion, the use of nitrate reduced to 50 mg kg−1 in fermented loins allows to obtain a product with properties similar to the product with 150 mg kg−1 of nitrate, especially in terms of its physicochemical properties and lipid oxidation.

Effect of Non-Condensable Gasses on the Performance of a Vacuum Thermochemical Reactor

A promising heat storage technique is based on thermochemical materials (TCM). Such materials are often used in closed systems under vacuum conditions, which is demonstrated in several projects in the European H2020 R&D programs. In this type of systems, non-condensable gasses (NCG) may have a significant effect on the reactor performance. This paper considers the potential effects of NCG on vacuum TCM reactor performance in detail. Water is used as working material to study NCG. Both experiments and numerical simulations show that the effect of NCG cannot be neglected. A small amount of NCG in a vacuum setup will significantly reduce the evaporation/condensation rate. It will transform the transport process from convection-based into diffusion-based in case the pressure of NCG at the condenser surface is equal to the pressure difference between the evaporator/condenser. Designing a stable vacuum storage system, puts high demands on leak tightness of the reactors but also on avoiding NCG release originating from TCM and any used material in the reactor (like coatings and glue). Additional free volume in the reactor will help to reach the demands of stable performance over longer working periods but decreases system energy density, being a crucial KPI. With help of our model, the performance of a system can be determined.

The effect of increased methionine in broiler chicken diets on the quality of breast muscles at different times of vacuum storage under refrigeration

The aim of the study was to determine the effect of different levels of DL-methionine in feed for broiler chickens on the quality of vacuum-packed breast muscles stored under refrigeration. The material for the study was 72 breast muscles from 35-day-old broiler chickens fed diets with varying content of DL-methionine. The control group received a basal diet without additional DL-methionine, while the experimental groups received compound feeds supplemented with 0.08% or 0.24% DL-methionine. At 35 days of age, 24 birds from each group were randomly selected and experimentally slaughtered. After the carcasses were dissected, 8 right breast muscles were selected from each feeding group and analysed immediately after cooling. The remaining muscles were vacuum-packed and after 7 and 14 days of storage physicochemical and sensory analyses were performed to assess the influence of storage time on changes in their quality. The methionine level was not found to affect the sensory properties of the breast muscles, but the meat of birds receiving a higher level of this amino acid had better shear force and water-holding capacity in comparison to the control group. After just 7 days, the results of the analyses of vacuum-packed refrigerated muscles showed a negative effect of storage time on the capacity of the muscle tissue to bind water, as well as changes in the proportion of red colour in the muscles. However, it is worth noting that the sensory quality of the muscles deteriorated only after 14 days of storage.